California's retreat from its zero-emission targets eases the pressure on utilities, making time for a fresh look at public and private efforts.
Electric vehicles (EVs) hold interest...
Plug-in hybrids usher a new era for wind power.
1970s, and related to the currently-popular hybrid electric vehicles—use sophisticated battery technology to power most short-distance trips and are recharged from the electric grid. This recharging generally occurs at night, when vehicles typically sit idle (most likely by plugging the vehicles into a standard electrical outlet). PHEVs still carry on-board fuel— i.e., gasoline or diesel—for occasions when a trip exceeds the range of the battery. That option, however, might not be needed very often for most drivers during a typical week: Data from the U.S. Department of Transportation show that 78 percent of commuters travel 40 miles or less each day—a distance that corresponds well with the expected battery-only range of PHEVs.
Obviously, the use of wind energy to charge PHEVs can result in emissions reductions. But before examining those benefits, it’s worthwhile to take a look at the impact of PHEVs on emissions even without wind-power growth. The good news is that PHEVs are capable of putting a dent in emissions even without the extra help of wind power.
A report from the Pacific Northwest National Laboratory found that replacing 73 percent of the U.S. light-duty vehicle fleet with PHEVs would reduce oil consumption by 6.2 million barrels a day, cutting the need for imported oil by about 50 percent. 2 Other studies confirm this, including one conducted jointly by the Electric Power Research Institute (EPRI) and the Natural Resources Defense Council (NRDC). That report found that replacing 60 percent of light vehicles in the U.S. with plug-in vehicles by 2050 would result in electricity consumption rising only about 8 percent. The emissions impact: Net carbon dioxide reductions of 450 million metric tons annually, equivalent to taking 82 million cars off the road. 3 The EPRI-NRDC report analyzed nine scenarios based on three sets of electricity-sector emissions profiles and three levels of PHEV adoption rates for the nation’s light-duty vehicles:
• Annual GHG emissions are reduced in all nine scenarios, when factoring in all life-cycle emissions (“well to wheels”)—dispelling the misperception that charging of PHEV batteries would increase emissions from an overall standpoint;
• Cumulative GHG emissions reductions range from 3.4 to 10.3 billion metric tons over the 2010 to 2050 time period; and
• Emissions reductions would occur in all regions of the country.
Further, when wind power provides an even larger share of the generation mix that’s recharging the fleet of PHEV batteries, environmental benefits increase accordingly. In the 20-percent wind scenario, as more wind generation comes online each year, more energy to charge PHEVs overnight would come from wind power. Indeed, the growth of PHEVs would allow wind power to go well beyond the 20-percent penetration mark, and possibly before the year 2030 outlined in the DOE report. The result is more electricity from clean energy sources such as wind power, and less pollution released into the atmosphere.
A key factor related to PHEVs that significantly decreases net emissions is that electric motors are several times more efficient than gasoline internal combustion engines. According to studies from EPRI, the batteries in a typical PHEV will draw about